Four shades of detachment: Regulation of floral organ abscission

Kim, Joonyup

doi:10.4161/15592324.2014.976154

Cited by 77 publications

(89 citation statements)

References 67 publications

(194 reference statements)

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“…In phase 3 cell separation is initiated. Finally in phase 4 abscission zone cells become enlarged and differentiated [36]. Interestingly, in pathogen-triggered leaf abscission hae hsl2 mutants are only deficient in cell separation.…”

Section: Discussionmentioning

confidence: 99%

Leaf shedding as a bacterial defense in Arabidopsis cauline leaves

Patharkar

Gassmann

Walker

2017

Preprint

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Plants utilize an innate immune system to protect themselves from disease. While many molecular components of plant innate immunity resemble the innate immunity of animals, plants also have evolved a number of truly unique defense mechanisms, particularly at the physiological level. Plant's flexible developmental program allows them the unique ability to simply produce new organs as needed, affording them the ability to replace damaged organs. Here we develop a system to study pathogen-triggered leaf abscission in Arabidopsis. Cauline leaves infected with the bacterial pathogen Pseudomonas syringae abscise as part of the defense mechanism. Pseudomonas syringae lacking a functional type III secretion system fail to elicit an abscission response, suggesting that the abscission response is a novel form of immunity triggered by effectors. HAESA/HAESA-like 2, INFLORESCENCE DEFICIENT IN ABSCISSION, and NEVERSHED are all required for pathogen-triggered abscission to occur. Additionally phytoalexin deficient 4, enhanced disease susceptibility 1, salicylic acid induction deficient 2, and senescence-associated gene 101 plants with mutations in genes necessary for bacterial defense and salicylic acid signaling, and NahG transgenic plants with low levels of salicylic acid fail to abscise cauline leaves normally. Bacteria that physically contact abscission zones trigger a strong abscission response; however, long distance signals are also sent from distal infected tissue to the abscission zone, alerting the abscission zone of looming danger. We propose a threshold model regulating cauline leaf defense where minor infections are handled by limiting bacterial growth, but when an infection is deemed out of control, cauline leaves are shed. Together with previous results our findings suggest that salicylic acid may regulate both pathogen-and drought-triggered leaf abscission.

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Section: Discussionmentioning

confidence: 99%

Leaf shedding as a bacterial defense in Arabidopsis cauline leaves

Patharkar

Gassmann

Walker

2017

Preprint

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“…Third, an enzymatic hydrolysis of the abscission zone’s middle lamella takes place and AZ cells begin to enlarge. Finally, the abscission scar further differentiates and seals itself (Kim, 2014). The hydrolysis phase has been thoroughly reviewed and will not be discussed in detail here (Niederhuth et al ., 2013; Kim, 2014).…”

Section: The Abscission Signaling Network In Arabidopsismentioning

confidence: 99%

“…Finally, the abscission scar further differentiates and seals itself (Kim, 2014). The hydrolysis phase has been thoroughly reviewed and will not be discussed in detail here (Niederhuth et al ., 2013; Kim, 2014). A model of the physiological phases of abscission is shown in Figure 1.…”

Section: The Abscission Signaling Network In Arabidopsismentioning

confidence: 99%

“…Abscission zone cells are depicted in color where green represents neutral cytosolic pH and blue represents alkaline pH. This figure was adapted and updated from (Kim, 2014).…”

Section: The Abscission Signaling Network In Arabidopsismentioning

confidence: 99%

“…In drought triggered-abscission, the final size of AZ cells that have a sealed scar are not noticeably larger than AZ cells at the moment of first cell separation (Patharkar and Walker, 2016). Previous reviews suggest that floral organ AZ cell enlargement only happens after cell separation is complete (Kim, 2014). This notion is likely due to the fact that floral organ AZ cells cannot be visualized nondestructively prior to abscission because sepals and petals cover the AZs.…”

Section: Physiology Hormones and The Big Picture Of Abscissionmentioning

confidence: 99%

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Advances in abscission signaling

Patharkar

Walker

2017

Preprint

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Abscission is a process in plants for shedding unwanted organs such as leaves, flowers, fruits, or floral organs. Shedding of leaves in the fall is the most visually obvious display of abscission in nature. The very shape plants take is forged by the processes of growth and abscission. Mankind manipulates abscission in modern agriculture to do things like prevent pre-harvest fruit drop prior to mechanical harvesting in fruit orchards. Abscission occurs specifically at abscission zones that are laid down as the organ that will one day abscise is developed. A sophisticated signaling network initiates abscission when it is time to shed the unwanted organ. In this article, we review recent advances in understanding the signaling mechanisms that activate abscission. Physiological advances and roles for hormones in abscission are also addressed. Finally, we discuss current avenues for basic abscission research and potentially lucrative future directions for its application to modern agriculture.

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Inflorescence Abscission Zones in Grasses: Diversity and Genetic Regulation

Kellogg

2018

Annual Plant Reviews Online

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Abscission of the fruit and associated floral structures, also called shattering, is a crucial survival strategy for propagation of wild grasses, and the loss of shattering in cereal crops is one of the most important domestication traits. Abscission occurs in specialised cell layers called the abscission zone (AZ). The fruit and floral AZs in different grass species are morphologically and anatomically diverse. In this article, we take a comparative approach and summarise our knowledge of the AZs in grasses at morphological, anatomical, and genetic levels. We show that the AZs in different grass species differ in terms of the position along the inflorescence, cell shapes of the AZ, and cell wall properties in the AZ, indicating distinctive mechanisms of abscission in these species. We further review the progress in illuminating the genetic regulation of AZ development in a few cereal crops. Current data suggest both conserved regulatory molecular mechanisms within grasses and between grass and dicot models, as well as unique gene functions currently found only in certain grass species. The rapid growth of genomic sequencing and molecular technologies will further advance our understanding of the molecular regulatory network and evolution of the AZ development.

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Four shades of detachment: Regulation of floral organ abscission

Cited by 77 publications

References 67 publications

Leaf shedding as a bacterial defense in Arabidopsis cauline leaves

Leaf shedding as a bacterial defense in Arabidopsis cauline leaves

Advances in abscission signaling

Inflorescence Abscission Zones in Grasses: Diversity and Genetic Regulation

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